This invention relates to writing pads for entering information into data processors such as microcomputers.
Alphanumeric information is commonly entered into microcomputers by typing on a keyboard. Each keystroke is converted into a coded digital signal, such as an ASCII code. In some cases the keys are replaced by an array of key positions of a membrane type switch. Scanning circuitry is used to scan the rows and columns of key positions to determine which key position is being touched.
Writing pads enable a user to enter a sketch into the data processor by "writing" on the surface of the pad. As each point on the sketch is written, the pad senses its location and delivers analog signals corresponding to that location. The analog signals can be converted into digital signals from which the two-coordinate positon of the point can be determined.